1. Field of the Invention
This invention relates to a magnus measuring apparatus and, more particularly, to a magnus measuring apparatus for use in a magnus method for primary screening of pharmaceutically active substances.
2. Description of the Prior Art
The magnus method is a measuring method for measuring effects of pharmaceutical solutions against a biological specimen such as a skeleton muscle, a nerve muscle, an atrium or smooth muscle and the like being capable of performing an elastic movement, wherein said biological specimen is immersed in a nutritious solution by maintaining a tension being applied thereto and thereby reacted with various pharmaceutical solutions as keeping the function of the specimen.
The effect on the specimen by the pharmaceutical solution is, for instance, evaluated by measuring an amount of elongation of the specimen through a change of tension or a change of length thereof. Accordingly, there has been used in the prior art is a magnus measuring apparatus which can afford to measure an amount of elongation as well as a beat rate of the specimen by way of transferring a change of tension of the specimen into an electric signal.
In the prior art magnus measuring apparatus, a receptacle called a magnus tube for containing a nutritious solution as well as a pharmaceutical solution is employed, the specimen is provided with strings at both ends thereof, and thereby the lower end of the string is hooked on a projection formed in the magnus tube whilst the upper end of the string is secured to a transducer. The transducer is then moved up and down against the magnus tube for applying a tensile force to the specimen. In measuring, a periodic change of tension based on the elastic movement of the specimen is recorded by a pen recorder or an equivalent in accordance with an electric signal derived from the transducer which moves correspondingly with the tensile force applied on the specimen.
In case of employing a transducer which converts a tension to an electric signal, it is required to keep an initial tension to be applied on the specimen constant at the time when the specimen is immersed in a nutritious solution. That is, in such type of measuring method, whenever a type of a pharmaceutical solution is changed, the solution in the tube is replaced with another solution and thereby the specimen is required to be washed before immersing, and thus the initial tension of the specimen to be immersed in a new nutritious solution should always be set to a constant value.
Heretofore, in order to retain the constant initial tension for the specimen, for instance, if the transducer is mounted on a stud with use of a mounting screw, there required are repetitive operations of tightening or loosening of the mounting screw in adjusting a vertical position of the transducer by confirming the tension being applied to the specimen with reference to, for an example, a chart recorded by a pen-recorder in accordance with a converted electric signal which is derived from the transducer in response to the tension of the specimen.
In accordance with the prior art magnus measuring apparatus, a measured value of the tension applied on the specimen have to be read from the recorded chart with use of calipers and the like, this results in a time-consumption and, as it has been described above, the setting operation for the constant initial tensioning of the specimen has been a problem. Especially, in case of performing various tests simultaneously by using a plurality of specimens, there caused are a considerable time-comsumption and an inconvenience in operation.
Further, there is a need of automating the initial setting operation, however, in the initial setting, it is necessary to set the tension of the specimen to a bottom value of the tensile force varying in a periodic manner, thus the beats of the specimen as well as the bottom value thereof should be detected automatically in advance of automating the initial setting.
It is therefore an object of this invention to solve such problems encountered in the prior art and to provide a magnus measuring apparatus wherein the initial setting operation is automated.
It is another object of this invention to provide a magnus measuring apparatus wherein the initial setting operation is automated in such a manner as to vary a driving mode of a motor from a low to high speed operation in response to a control signal derived from a control unit in order to achieve a high speed automation.
It is still another object of this invention to provide a magnus measuring apparatus wherein a threshold value being set preliminarily in the initial setting can be renewed based on a detected tensile force being applied on a specimen.
It is a further object of this invention to provide a magnus measuring apparatus wherein a peak of the tensile force causing from beats of a specimen is detected after renewing a threshold value being set preliminarily.
It is still further object of this invention to provide a magnus measuring apparatus wherein a bottom value of the tensile force that varies periodically is so adjusted as to be within a preliminarily set extent of the tensile force simultaneously with detecting a peak of the tensile force causing from beats of a specimen after renewing a threshold value being set preliminarily.